1. Field of the Invention
The present invention relates to a plastic sheet, and in particular to a plastic sheet comprising a copolyester which contains 45-50 mole % monomer units derived from a first aliphatic diol, 45-50 mole % monomer units derived from a first aromatic dicarboxylic acid, and 0.5-5 mole % monomer units derived from a second aliphatic diol and/or a second aromatic dicarboxylic acid. The present invention further relates to molded articles containing the plastic sheet of the present invention.
2. Description of the Related Art
Since the aforementioned copolyester contains a minor amount of the comonomers, the copolyester exhibits a low crystallization rate in comparison with a polyester that does not contain the comonomers. As a result, it is generally possible to extrude the copolyester to a plastic sheet having high luminous transmittance and low haze.
A disadvantage in utilizing this plastic sheet, however, is that the copolyester crystallizes during manufacture of the sheet, especially if the sheet is thick, resulting in inadequate luminous transmittance and unacceptable haze of the plastic sheet. Furthermore, the plastic sheet can be shaped into end products at elevated temperature only to a limited extent without the copolyester crystallizing. As a result, during the shaping process, the luminous transmittance of the sheet decreases and the haze of the plastic sheet increases.
It is, therefore, an object of the present invention to provide a plastic sheet that does not have the aforementioned disadvantages or at least reduces the magnitude of the aforementioned disadvantages.